A need exists for improving the performance of a variety of electronic devices such as, for example, organic light emitting devices such as organic light emitting diodes (OLEDs) as well as photovoltaic devices such as organic photovoltaics (OPVs). One way this need is met is through development of new materials for these devices that enhance device output and prolong device lifetime. A particularly promising approach lies in the development of new materials for device layers such as the hole injection, hole transport, and hole extraction layers.
In particular, improvements in technologies for hole injection and/or hole transport in these devices is especially desirable. State of the art organic electronic devices generally still can benefit from hole injection layers (HILs) and/or hole transport layers (HTLs) within the device to optimize charge flow through the device, and separation or recombination of electrons and holes. Hole injection layers and hole transport layers can present difficult problems, however, because of the solubilities of the component materials (or lack thereof) in processing solvents, and because of the dopants and/or acids needed for HIL performance. Dopants and acids should be chosen judicially to minimize their contributions to device operation (e.g., efficiency and degradation).
Further, a need is recognized to exist wherein the hole injection and/or hole transport layer components are processable from selected solvents such as, for example, non-aqueous and/or aprotic high-purity solvent in order to minimize deleterious effects on device operation. In addition, a need also exists to develop layers that are compatible with the deposition of subsequent layers by vapor or solution processes.